Getting the skinny on dietary fat: the good, the bad and the fantastical

Learn to separate the fat from fiction with this quick guide.

Once upon a time, fat was the enemy. Eating as little of it as possible was supposed to keep us trim and free of heart disease and diabetes. For some time now we have understood that fat is an essential part of a healthy diet. In fact, new research shows that drastically cutting fat may not improve heart health. All this flip-flopping has left many people confused. So what is the truth about fat?

The benefits of fat in the diet

Without fat in the diet, vitamins A, D, E and K, or fat soluble antioxidants like beta-carotene and lycopene, could not be absorbed, as they all need dietary fat to propel them through the walls of the digestive tract and into the bloodstream. Fat also provides essential fatty acids (discussed below). Fat is a beauty essential; it keeps nails, skin and hair from drying out. Fat also carries the compounds that give foods their aroma and flavour.

But won’t eating fat make you fat?

That depends. If you eat more calories than you burn, weight gain occurs, whether the source is fat, carbohydrates, protein or alcohol. But it is easier to gain weight when you load up on fat, since 1 gram of fat contains more than twice as many kilojoules as 1 gram of protein or carbohydrate. Still, Australians are not getting heavier because they are eating more fat (they aren’t), but because they are consuming more kilojoules and doing less exercise. Many of these kilojoules come from alcohol, cakes, confectionery, cereal bars, pastries, biscuits and soft drinks (high sugar, no fat).

The lesson: even low-fat foods, eaten in abundance, lead to weight gain.

How much fat?

Some fat is vital to good health. At least one or two tablespoons of healthy oil or some nuts, seeds or avocado should be included every day. Experts now agree that the type of fat you eat is more important than the amount. So the aim is to replace unhealthy fats with healthy ones. If weight loss is recommended, the whole diet should be assessed and an accredited practising dietitian can help with this.

Which fats are healthy?

Technically, oils are liquid at room temperature whereas fats are solid, but the terms are used interchangeably. From a practical perspective, if an oil or ‘fat’ is liquid at room temperature, it’s more likely to contain healthy fats.

Monounsaturated fats are found in olive oil, canola oil, peanut oil, sesame oil, avocado and nuts (almonds, cashews, hazelnuts, macadamias, pecans, peanuts and pistachios). When replacing saturated fats in the diet, these fats decrease total and LDL cholesterol.

Polyunsaturated fats include omega-6 and omega-3 fatty acids, which are essential in the diet as your body can’t make these on its own. They decrease LDL cholesterol and can increase the HDL cholesterol.

Omega-6 fatty acids are found in corn, sunflower and cottonseed oils – which are used in many processed foods.

Omega-3 (DHA/EPA) provides benefits for heart and eye health and is abundant in oily fish. Since most people don’t get enough omega-3, it is advisable to eat fish 2–3 times a week – ideally, salmon, tuna, trout, mackerel, sardines or herring.

Omega-3 (ALA) is found in canola oil, flaxseeds and walnuts, but conversion to DHA or EPA in the body is minimal. Omega-3 supplements can also help boost intake.

Fats to avoid

Saturated and trans fats have both been linked to high cholesterol and heart disease. They are solid at room temperature and increase LDL cholesterol. Trans fats also decrease HDL cholesterol.

Sources of saturated fat include processed and fatty meats, fried take-away foods, pastries, store-bought cakes and biscuits, butter, cheese, cream cheese, sour cream, cream, ice cream, full cream milk, poultry skin, shortening, coconut milk, coconut oil, palm oil, palm kernel oil and cocoa butter.

Trans fat is created when liquid oil undergoes hydrogenation, a chemical process that extends its shelf life and provides structure to foods. It is common in many foods that also contain saturated fat. Trans fat consumption in Australia is relatively low due to the types of fats/oils used here. Minimising foods containing saturated fats will also limit trans fat intake.

The truth about coconut oil

Conduct a quick Google search and you’ll find miraculous claims about a tropical fat that has become increasingly popular among health-conscious consumers in recent years. People make a lot of claims about coconut oil, but there is no well-designed, peer-reviewed, credible scientific evidence to show that coconut oil speeds metabolism, promotes weight loss, cures Alzheimer’s disease, improves brain function, or improves heart health.

In addition, no evidence exists to prove virgin coconut oil is less damaging to your heart than other varieties. More importantly, over 90 per cent of the fat in coconut oil is saturated fat. Decades of research have determined that saturated fat is detrimental to your heart and blood vessels. Use it in moderation, if at all.

So the message regarding fats has changed over the years. We know now that it’s important to choose healthy fats in the right amounts, that these should replace unhealthy fats in the diet, and that there are some essential dietary fats that should be consumed as part of a healthy diet. Accredited practising dietitians can provide nutrition advice to your patients, tailored to their individual needs.

Arlene Normand is an Accredited Practising Dietitian (APD) with more than 15 years’ experience. To find an APD in your local area, call 1800 812 942 or visit the ‘Find an APD’ section of the DAA website.

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